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SubjectRe: Uptime timer-wrap
On Sep 05, 2002  16:16 -0400, Richard B. Johnson wrote:
> I tried to simulate your observation by making a driver that
> set the 'jiffies' count upon an 'open'. The idea was to get
> the jiffies count to something close to wrap so I didn't have to
> wait a long time.
> Anyway, I found that setting the jiffies count to more than a
> few hundred counts into the future, causes the machine to halt
> with no interrupts (no Capslock, no NumLock, no network ping, etc).
> The machine just stops and I don't understand why.
> spin_lock_irqsave(&xlock, flags);
> jiffies += 0x1000;
> spin_lock_irqrestore(&xlock, flags);
> ... works just fine, but, changing 0x1000 to 0x7fffffff causes
> the machine to stop as reported.
> Does anybody have a clue?

Yes, because now some kernel code is going to wait 147 days - 1s
or something like that to finish.

See Tim Schmielau <> patch for testing jiffies
wrap. It _initializes_ jiffies to a high pre-wrap value, maybe 5
minutes before wrap, instead of playing around with the jiffies value
after the system is running.

Cheers, Andreas
Andreas Dilger

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